The present invention relates generally to fuel tanks for vehicles and, more particularly, to a fuel permeation barrier fuel tank for a vehicle.
It is known to provide a fuel tank such as a plastic fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. In some vehicles, the plastic fuel tank has a fuel permeation barrier made of an ethylene vinyl alcohol copolymer (EVOH). While EVOH is effective against permeation of pure hydrocarbon fuels, it has a high permeability when used with alcohol containing fuels.
One commercial approach to resolve this concern regarding permeation is to thicken the walls of the fuel tank, which increases the weight, cost and reduces fuel capacity of the fuel tank. Therefore, it is desirable to provide a fuel tank for a vehicle that has a more effective fuel permeation barrier to prevent evaporative emission of hydrocarbon fuels and fuels containing alcohol. It is also desirable to provide a fuel permeation barrier fuel tank for a vehicle that significantly reduces evaporative emissions.
It is, therefore, one object of the present invention to provide a new fuel permeation barrier fuel tank for a vehicle.
It is another object of the present invention to provide a fuel tank that significantly reduces evaporative emission and cost in comparison to EVOH plastic tanks.
To achieve the foregoing objects, the present invention is a fuel permeation barrier fuel tank for a vehicle including a tank shell having a wall formed from a plurality of layers. The layers include at least an inner layer, an outer layer and a fuel permeation barrier layer between the inner layer and the outer layer and being made of either one of a polyvinylidene fluoride PVDF and a terpolymer material.
One advantage of the present invention is that a fuel permeation barrier fuel tank is provided for a vehicle that has a more effective fuel permeation barrier leading to less permeation and evaporative emissions. Another advantage of the present invention is that the fuel permeation barrier fuel tank uses polyvinylidene fluoride (PVDF) and a terpolymer of ethylene tetrafluoridexe2x80x94propylene hexafluoride-vinylidene fluoride (THV) as the material for the barrier layer. Yet another advantage of the present invention is that the THV has improved flexibility and improved crack resistance as compared to EVOH. Still another advantage of the present invention is that the fuel permeation barrier fuel tank significantly improves permeation resistance of the fuel tank to alcohol containing fuels and lowers cost of the fuel tank. A further advantage of the present invention is that the use of these materials in a plastic fuel tank improves fuel barrier properties and can lead to lighter tanks.